Cellulosic textile finishing



United States Patent 3,252,750 CELLULQSIC TEXTILE FINISHING Georg Heherlein and Fritz Munzel, both I of St. Gall,

Switzerland, assignors, by mesne assignments, to Heberlein & Co. A.G., Wattwil, St. Gall, Switzerland, a corporation of Switzerland No Drawing. Filed July 19, 1961, Ser. No. 147,380 Claims priority, application Switzerland, July 27, 1960, 8,695/60 The portion of the term of the patent subsequent to July 7, 1981, has been disclaimed 9 Claims. (Cl. 8116) This application is a continuation-in-part of US. application Serial No. 62,068, filed March 31, 1960, now US. Patent 3,140,197.

This invention relates to a novel finished cellulosic textile product and to a process for finishing cellulosic textiles employing ionizing radiation. The process is particularly applicable to the wash-and-Wear finishing of cellulosic textile materials. The latter term as employed herein is intended to include films, yarns, fibers, filaments or threads as such or in the form of cast sheets, woven, knit, felted or non-Woven [fabrics consisting of natural or regenerated cellulose, as Well as such fabrics which are made up of a major portion of cellulose or regenerated cellulose, but containing in addition a small quantity of non-cellulosic fibers, filaments, etc.

The process of the present invention is particularly directed to a method for improving the crease resistance (wash-and-wear) properties of the cellulosic textile, as measured by the crease angle, but the method also produces a substantial improvement in the tearing or tensile and abrasive strengths .of the materials treated in accordance herewith.

It is well known that in order to improve the crease resistance of natural or regenerated cellulose fabrics, for example cotton, rayon or mixed cotton and rayon goods, the fabric is impregnated with one or more well-known condensable substances, for example, a synthetic resin precondensate which is dispersed or dissolved in a carrier containing a condensation catalyst which is usually acidic. Following impregnation, the excess resin is squeezed out and the impregnated fabric is then subjected to temperatures above 100 C. for a period of time sufiicient to cure the resin. Textiles finished by this conventional technique at elevated temperature are substantially less durable than the unfinished or starting fabric. Conventional finishing imparts acceptable crease resistance, but at the expense of a marked reduction in fiber strength of the textile product, as evidenced either by appreciably reduced tensile or tearing strength or resistance to abrasion or both.

According to Heberlein et al., US. Patent 3,140,197, a method is suggested whereby the cellulosic textile to be finished is first treated with a condensable or resin-forming substance, for example a resin precondensate and subsequently subjected, to ionizing radiation, which irradiation causes condensation of the resin-forming substance on the textile. The method may be carried out with or without the usual condensation catalysts, and condensation occurs as a result of the treatment of the resin with ionizing radiation. Heat is not required. The product produced by the method of this earlier application 3,252,759 Patented May 24, 1966 ice exhibits substantially improved crease resistance as compared with the same textile finished by the conventional method above described. The tensile or tearing strength of the finished textile is in some instances, although not always, improved. Occasionally tensile strength is slightly reduced. In accordance with our said earlier application, the cellulosic textile its irradiated with the condensable or resinforming substance thereon, and it has been found that in many instances substantial doses of ionizing radiation are required, for example of the order of 0.5 10 to about 3x10 rads and even as high as 10' rads, in order to achieve the results desired by that finishing process. These doses of ionizing radiation, which of course depend upon the nature of the textile substrate itself and also upon the condensable substance applied to it, have the effect of degrading the cellul osic molecule thus detracting from certain of the desirable properties of the unirradiated or starting textile. While it is generally agreed that a finish superior to that of the convenventional method can be imparted to the textile by the method of our earlier application, there is still a need fior a method which will assure these superior results without application of an ionizing radiation dose sufiicient to appreciably degrade the cellulose.

Protective chemicals are a partial solution to the problem, but the fact remains that a certain direct irradiation does is required to condense the resins. Some of the resin-forming chemical compounds or resin precondensates which are employed in the wash-and-wear finishing of cellulosic textile fabrics, for example, are sensitive to direct ionizing radiation and suffer partial decomposition. That is to say the desirable condensation reaction which is facilitated by the ionizing radiation is at the expense of appreciable decomposition of certain of the condensable substances. For example, ureaformaldehyde and melamine-formaldehyde resin precondensates are typical radiation-sensitive materials which are partially decomposed as a result of direct irradiation.

The present invention provides a novel process which is an improvement upon the method described in our earlier application, and salient advantages thereover will be immediately apparent to those skilled in the art.

In accordance with the broadest aspects of the present invention, the cellulosic textile is preirradiated, that is to say the textile is initially subjected to ionizing radiation, after which a resin-forming substance or resin preoondensate is applied to the irradiated textile, after which the irradiated impregnate-d material is squeezed off and dried. It has been found that by following this sequence substantially lower total doses of ionizing radiation are required to effect condensation of the resin forming substance. Irradiation of the textile apparently creates active centers on the cellulose molecule which catalyze or otherwise effect condensation of the subsequently applied resin-forming material. Since irradiation precedes ap plication of the condensable finishing substance such material is not subjected to direct irradiation and does not suffer the aforementioned partial decomposition.

Furthermore, the present method enables one to carry out irradiation and impregnation or final finishing separately both as respects location and time. This is particularly important to the small finisher of cellulosic textiles who is not in a position to acquire and operate irradiation equipment. In accordance with the method of the present invention irradiation may be carried out at one location and impregnation at another, since the preirradiated cellulosic textile retains its ability to effect condensation of the resinforming substance after the passage of several days, which is an obvious advantage.

As noted above, according to the present method the cellulosic textile is subjected to a lower dose of ionizing radiation, more particularly to a dose between about 10 and 10 rads, and preferably 10 to 5 l0 rads. This is a very significant imprevement over prior art techniques since at these lower doses degradation of the cellulose molecule is very appreciably reduced. The ionizing radiation may be of the electromagnetic type, for example gamma or X-rays. Suitable sources of gamma include C0 burnt uranium slugs, fission products of U separated isotopes such as Cs etc. Alternatively, the ionizing radiation may consist of accelerated electrons, i.e. beta particles, of a relatively low particle energy, namely between about 0.05 and 1 mev., preferably between about 0.05 and 0.6 mev., which may be produced with the aid of the usual electron accelerators, such as the cascade, Van de Graaff, or linear types, or from radioactive substances such as Sr An important aspect of the present invention is the use of accelerated electrons of the aforementioned low energy values. It has been found that these low energy beta particles enable sufficient activation of the cellulosic molecule to achieve resin condensation without significant degradation of the cellulose. At energy levels above about 1 mev. and equivalent total doses very significant deterioration of the cellulose occurs. The importance of the use of low energy beta particles is set forth in the related application of Fritz Munzel, Serial No. 125,089, filed on even date herewith, and the information therein with respect to the use of low energy particles is herewith incorporated byreference.

It is also within the scope of the method of the present invention to irradiate the cellulosic textile to the aforemenioned total dose, prior to application of the resinforming substance, in the presence of a radiation sensitizer in contact withthe textile, as set forth in Munzel US. application Serial No. 111,900, filed May 2, 1961, of which the present application is also a continuation-in-part. The sensitizers described in this latter application contain molecular groups capable or absorbing ionizing radiation energy and resonating or transferring excitation energy to the cellulosic molecule or to the resin-forming substance which is subsequently imparted to the textile. The action of the sensitizers is to ultimately very greatly enhance the effect of ionizing radiation upon the resin-forming substance, While also by reason of their absorptive and resonating efficiency serving to reduce the total does which must be imparted to the textile. A variety of materials suitable as sensitizers are set forth in the aforementioned application, and a particularly preferred material is 1,4-diphenylbenzene. The sensitizers are preferably applied to the cellulosic textile by application from aqueous media followed by squeezing off and drying, with the sensitized textile then being ready for irradiation.

The term resin-forming substance as employed herein is to be understood as meaning a substance which can be condensed with itself, with another material also present or with the cellulosic molecule of the textile being treated. The term also may refer to a mixture of two or more such substances which may intercondense. Typical resin-forming substances are those customarily employed in the crease-proof finishing of cellulosic textiles, by conventional methods not employing irradiation. They are compounds which contain oxygen in the molecule or which contain sulphur in place of oxygen, as in urea and thiourea. Typical condensable or resin-forming substances include: precondensates of formaldehyde with urea, thiourea, ethyleneurea and its homologues, uron,

acetylenediurein and is derivatives, dicyandiarnide, melamine, phenol and its derivatives, methylolurea, methylolamines, as well as ketone-aldehyde precondensates, aziridinyl compounds, triazone derivatives and diglycide ethers. Particularly suitible resin-forming substances include N- substituted urea-formaldehyde resin precondensates such, in addition to ethyleneurea, as dioxyethyleneurea or N,N'- bis (methoxy-methyl uron. Tetrohydro- 1 ,3-bis (methoxymethy1-5-methyl-2(1)-s-triazone, 1 carbonyl 2,5 dimethoxy-4-ethyl-triazone-2,4,6 and other similar triazone derivatives may be employed. Mixtures of two or more of such resin-forming substances may of course be used if desired.

One of the important advances of the present invention, as well as that of application Serial No. 62,068 is the fact that heating is not required to effect resin formation or condensation of the finishing substance on the textile. The cellulosic material following application of the resin-forming substance is of course squeezed out and dried, and during the passage of the time consumed for these operations condensation of resin formation occurs. Heating is generally employed to facilitate drying of the treated textile, but temperatures are mainained below about 100 C. Typical drying temperatures range from about 60 to about C., as shown clearly in the following examples.

The method of the present invention can be applied to textiles of all kinds, but is particularly applicable to fabrics or sheet material. Woven or knit goods of native or regenerated cellulose or mixed native and regenerated cellulose, e.g. cotton and rayon, are especially improved by the present finishing method. The method is suitable primarily for the crease-proofing and the imparting of dimensional stability to the material. However, it is also possible to produce by this method permanent embossing effect, such as goffering, ribbing, schreinerizing or moire effects, as well a calendering effects, with or without friction.

The method can furthermore be applied to fine cotton or regenerated cellulose fabrics, in which stiffening and/ or transparency have been achieved by a treatment with concentrated sulfuric acid, cuprammonium solution or sodium zincate cellulose solution, and with such fabrics good crease resistance effects can be achieved without a decrease in fiber strength. In fact with substantially all fabrics improved crease resistance is accompanied by substantially improved tensile and abrasive strength. Particularly significant improvements are achieved with the fine or stiffened and transparentized fabrics, where significant degradation of the cellulose as a result of excessive doses of ionizing radiation would be immediately apparent. The foregoing improvements in the finished cellulosic textile fabric are accompanied by retention of a pleasant soft hand.

The method of the present invention can of course be applied to. textile yarns, filaments, fibers or threads, and good crease resistance and dimensional stability can be achieved in fabrics constructed of relatively highly twisted yarns, such as voile and marquisette, which ordinarily have a very strong tendency to shrink.

The method of the present invention will be further apparent from the following typical examples which illustrate practical applications of the method and describe certain characteristics of the novel finished textile products.

Example I A spun rayon muslin fabric which had been pretreated in the usual manner was immersed in a water bath containing about 1% of 1,4-diphenylbenzene at 20 C. and thereupon dried at 60-70 C. The fabric was then subjected to a stream of accelerated electrons having a particle energy of 0.12 mev. to a total dose of 10 rads. The irradiated fabric was thereupon impregnated with a 15% aqueous solution of aziridinyl phosphoniumoxide, squeezed out and dried at 7080 C., after which it was again washed with water and similarly dried. The mechanical properties of the thus finished fabric, the starting material, and the fabric which had been simply sensitized and irradiated are shown in the following table:

Tearing strength was determined with an Elmendorf Tearing Tester on strips 2.5 cm. wide and 16.5 cm. long. Abrasive strength was measured with an apparatus containing a disc covered with a standardized Wool cloth which was rotated on the surface of the fabric until the fabric failed, and the number of revolutions noted. Crease angles were determined as follows: Strips of material 3 x 5 cm. were folded in the warp or fill direction, respectively, and placed under a 1 kg. weight for one hour. After removal of the weight the material was left unweighted for fifteen minutes and the crease angle thereupon measured.

Example II Crease angle Tearing Abrasive in degrees strength in G. strength in number of revolutions Warp Fill Warp Fill Starting material 49 43 680 590 16, 770 Irradiated material. 47 37 632 564 433 Irradiated material treated with resin precondensate 100 105 960 730 30, 840

Example 111 A cotton muslin fabric was parchmentized with 52 B. sulfuric acid at- 15 C. for ten seconds and thereupon aftermercerized with 30 B. sodium hydroxide for fifteen seconds. The material was washed until neutral, then immersed in a water bath containing about 1 g. of 1,4-diphenylbenzene at 20 C., and subsequently dried. The fabric was then subjected to the action of accelerated electrons of a particle energy of 0.12 mev. to a total dose of rads. Thereupon the fabric was impregnated with a aqueous solution of aziridinyl phosphoniumoxide, squeezed out, dried at 70-80 C., washed and dried again. The mechanical properties of the thus finished fabric and the starting material were as follows:

6 Example IV A cotton voile fabric was treated with an aqueous solution'containing about 1% 1,4-diphenylbenzene at 20 C., dried at 60-70 C. and thereupon subjected to the action of accelerated electrons of a particle energy of 0.12 mev. to a total dose of 5X10 rads. The fabric was subsequently impregnated with an aqueous solution containing 150 g. of a melamine-formaldehyde resin precondensate in 1 liter of water, squeezed out and dried at 7080 C., washed and dried again at the same temperature. The mechanical properties of the thus finished fabric and the starting material were as follows:

Crease angle Tearing Abrasive in degrees strength in G. strength in number of revolutions Warp Fill Warp Fill Starting material 47 52 Not measurable 1, 990 Irradiated material 90 1, 808 1, 016 7, 443

It will be apparent that the poplin of Example II is a reasonably heavy cotton fabric as evidenced by its initial tearing and abrasive strength, and yet these physical properties, in addition to the crease angle, were very substantially increased by treatment in accordance with the present invention. The parchmentized muslin of Example III and the cotton voile of Example IV are inherently fragile fabrics, but there was a three-fold increase in the crease angle of the muslin and virtual doubling of the crease angle of the voile, accompanied by doubling and quadrupling of the abrasive strength of the respective materials. Very substantial improvements in tearing strength were also obtained.

We claim:

1. A method of finishing a cellulosic textile, which comprises first subjecting the textile to high energy ioniz ing radiation to a total dose between about 10 and i0 rads, whereby said textile is rendered capable of condensing a condensable resin-forming substances, subsequently impregnating the thus irradiated textile with a creaseresistance imparting condensable resin-forming substance and permitting the same to condense in contact with said textile.

2. A method as set forth in claim 1 wherein the condensable resin-forming substance comprises an oxygencontaining compound.

3. A method as set forth in claim 1 wherein the irradiated textile is impregnated with a crcase-resistance imparting condensable resin-forming substance in aqueous media.

4. A method as set forth in claim 1 wherein the total dose of high energy ionizing radiation imparted to the textile is between about 10 and 5 10 rads.

5. A method as set forth in claim 1 wherein following impregnation of the textile the impregnated textile is dried at elevated temperatures up to about C.

6. A method of finishing a cellulosic textile which comprises subjecting the textile to accelerated electron radiation of a particle energy between about 0.05 and 1 mev. to a total dose between about 10 and 10 rads, subsequently impregnating the irradiated textile with a condensable wash-and-wear resin-forming substance and permitting the same to condense in contact with said textile.

7. A method for imparting excellent crease resistance to stiffened, transparentized and parchmentized cellulosic textiles, which comprises first subjecting the textile to high energy ionizing radiation to a total dose between about 10 to 5 l0 rads, subsequently impregnating the 7 thus irradiated textile with a condensable crease-resistance imparting resin-forming substance and then drying the irradiated impregnated textile below about 100 C.

8. A crease-resistant, cellulosic textile finished by the process of claim 1.

9. A crease-resistant fine cellulosic fabric finished by the process of claim 7.

References Cited by the Examiner UNITED STATES PATENTS 2,956,899 10/1960 Cline 117-47 2,998,329 8/1961 Sovish. 3,101,276 8/1963 Hendricks 117-56 8 FOREIGN PATENTS 546,817 10/1956 Belgium.- 75s,735 10/1956 Great Britain.

OTHER REFERENCES NORMAN G. TORCHIN, Primary Examiner.

RICHARD D. NEVIUS, Examiner. 

1. A METHOD OF FINISHING A CELLULOSIC TEXTILE, WHICH COMPRISES FIRST SUBJECTING THE TEXTILE TO HIGH ENERGY IONIZING RADIATION TO A TOTAL DOSE BETWEEN ABOUT 10**4 AND 10**6 RADS, WHEREBY SAID TEXTILE IS RENDERED CAPABLE OF CONDENSING A CONDENSABLE RESIN-FORMING SUBSTANCES, SUBSEQUENTLY IMPREGNATING THE THUS IRRADIATED TEXTILE WITH A CREASERESISTANCE IMPARTING CONDENSABLE RESIN-FORMING SUBSTANCE AND PERMITTING THE SAME TO CONDENSE IN CONTACT WITH SAID TEXTILE. 